Mesoscale Iron Enrichment Experiments 1993-2005: Synthesis and Future Directions

Boyd, Philip W.; Jickells, Timothy D.; Law, Cliff S.; Blain, Stéphane; Boyle, E. A.; Buesseler, Ken O.; Coale, Kenneth H.; Cullen, John J.; Baar, H. J. W. de; Follows, Michael J.; Harvey, Mike; Lancelot, Christiane; Levasseur, Maurice; Owens, N. P. J.; Pollard, Raymond T; Rivkin, Richard B.; Sarmiento, Jorge L.; Schoemann, Véronique; Smetacek, Victor; Takeda, Shigenobu; Tsuda, Atsushi; Turner, Suzanne M.; Watson, Andrew J.

doi:10.1126/science.1131669

Cited by 1,287 publications

(1,017 citation statements)

References 40 publications

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“…However, the SOFeX-South experiment revealed an increase of particle fluxes after fertilisation, which resulted in F Th of $ 1800 dpm m À 2 d À 1 at the MLD . The variability within the plankton community structure and different sampling time strategies among these experiments most likely played a crucial role in the variety of results obtained (Boyd et al, 2007;Buesseler et al, 2004).…”

Section: Results and Comparison With Other Studiesmentioning

confidence: 99%

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Roca‐Martí

Puigcorbé

Iversen

et al. 2017

Deep Sea Research Part II: Topical Studies in Oceanography

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a b s t r a c tCarbon fixation by phytoplankton plays a key role in the uptake of atmospheric CO 2 in the Southern Ocean. Yet, it still remains unclear how efficiently the particulate organic carbon (POC) is exported and transferred from ocean surface waters to depth during phytoplankton blooms. In addition, little is known about the processes that control the flux attenuation within the upper twilight zone. Here, we present results of downward POC and particulate organic nitrogen fluxes during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean in summer 2012. We used thorium-234 ( 234 Th) as a particle tracer in combination with drifting sediment traps (ST). Their simultaneous use evidenced a sustained high export rate of 234 Th at 100 m depth in the weeks prior to and during the sampling period. The entire study area, of approximately 8000 km 2 , showed similar vertical export fluxes in spite of the heterogeneity in phytoplankton standing stocks and productivity, indicating a decoupling between production and export. The POC fluxes at 100 m were high, averaging 26 715 mmol C m À 2 d À 1 , although the strength of the biological pump was generally low. Only o 20% of the daily primary production reached 100 m, presumably due to an active recycling of carbon and nutrients. Pigment analyses indicated that direct sinking of diatoms likely caused the high POC transfer efficiencies ( $ 60%) observed between 100 and 300 m, although faecal pellets and transport of POC linked to zooplankton vertical migration might have also contributed to downward fluxes.

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Section: Results and Comparison With Other Studiesmentioning

confidence: 99%

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Roca‐Martí

Puigcorbé

Iversen

et al. 2017

Deep Sea Research Part II: Topical Studies in Oceanography

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“…Over 30 years of research has demonstrated that Fe limitation controls the efficiency of the biological pump and the structure of phytoplankton communities in the SO (e.g., Martin, 1990;Coale et al, 2003;De Baar et al, 2005;Maldonado et al, 2005;Blain et al, 2007;Boyd et al, 2007;Smetacek et al, 2012). However, only the biologically active pool (defined here as bioavailable) is the fraction that can be effectively taken up by microorganisms to support their nutrient-dependent metabolic processes and growth (Hassler et al, 2012).…”

Section: Iron (Fe) Limitationmentioning

confidence: 99%

Southern Ocean phytoplankton physiology in a changing climate

Petrou

Kranz

Trimborn

et al. 2016

Journal of Plant Physiology

103

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Please cite this article in press as: Petrou, K., et al., Southern Ocean phytoplankton physiology in a changing climate. J Plant Physiol (2016), http://dx.doi.org/10.1016/j.jplph.2016.05.004 ARTICLE IN PRESS a b s t r a c tThe Southern Ocean (SO) is a major sink for anthropogenic atmospheric carbon dioxide (CO 2 ), potentially harbouring even greater potential for additional sequestration of CO 2 through enhanced phytoplankton productivity. In the SO, primary productivity is primarily driven by bottom up processes (physical and chemical conditions) which are spatially and temporally heterogeneous. Due to a paucity of trace metals (such as iron) and high variability in light, much of the SO is characterised by an ecological paradox of high macronutrient concentrations yet uncharacteristically low chlorophyll concentrations. It is expected that with increased anthropogenic CO 2 emissions and the coincident warming, the major physical and chemical process that govern the SO will alter, influencing the biological capacity and functioning of the ecosystem. This review focuses on the SO primary producers and the bottom up processes that underpin their health and productivity. It looks at the major physico-chemical drivers of change in the SO, and based on current physiological knowledge, explores how these changes will likely manifest in phytoplankton, specifically, what are the physiological changes and floristic shifts that are likely to ensue and how this may translate into changes in the carbon sink capacity, net primary productivity and functionality of the SO.

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“…3.3.3.1 High Latitude HNLC Regions In certain regions that are known as high nutrientlow chlorophyll (HNLC) regions (Boyd et al 2007), some trace nutrients (notably iron) may remain low, even when other nutrients such as nitrogen, phosphorus and silica are available, limiting phytoplankton production. In HNLC regions in high latitudes (including parts of the Pacific and the Southern Ocean), the correlation between chlorophyll and SST may become weak or negative, indicating that phytoplankton growth is predominantly limited by nutrient availability rather than light availability.…”

Section: Regional Variationsmentioning

confidence: 99%

Causes of the Regional Variability in Observed Sea Level, Sea Surface Temperature and Ocean Colour Over the Period 1993–2011

et al. 2016

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We analyse the regional variability in observed sea surface height (SSH), sea surface temperature (SST) and ocean colour (OC) from the ESA Climate Change Initiative datasets over the period [1993][1994][1995][1996][1997][1998][1999][2000][2001][2002][2003][2004][2005][2006][2007][2008][2009][2010][2011]. The analysis focuses on the signature of the ocean large-scale climate fluctuations driven by the atmospheric forcing and do not address the mesoscale variability. We use the ECCO version 4 ocean reanalysis to unravel the role of ocean transport and surface buoyancy fluxes in the observed SSH, SST and OC variability. We show that the SSH regional variability is dominated by the steric effect (except at high latitude) and is mainly shaped by ocean heat transport divergences with some contributions from the surface heat fluxes forcing that can be significant regionally (confirming earlier results). This is in contrast with the SST regional variability, which is the result of the compensation of surface heat fluxes by ocean heat transport in the mixed layer and arises from small departures around this background balance. Bringing together the results of SSH and SST analyses, we show that SSH and SST bear some common variability. This is because both SSH and SST variability show significant contributions from the surface heat fluxes forcing. It is evidenced by the high correlation between SST and buoyancy-forced SSH almost everywhere in the ocean except at high latitude. OC, which is determined by phytoplankton biomass, is governed by the availability of light and nutrients that essentially depend on climate fluctuations. For this reason, OC shows significant correlation with SST and SSH. We show that the correlation with SST displays the same pattern as the correlation with SSH with a negative correlation in the tropics and subtropics and a positive correlation at high latitude. We discuss the reasons for this pattern.

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Mesoscale Iron Enrichment Experiments 1993-2005: Synthesis and Future Directions

Cited by 1,287 publications

References 40 publications

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Southern Ocean phytoplankton physiology in a changing climate

Causes of the Regional Variability in Observed Sea Level, Sea Surface Temperature and Ocean Colour Over the Period 1993–2011

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